If Sta Rite made the tank, the bladder was doomed to a short life. I'm not sure what your plans are for welding more fittings on the tank, but I don't think that tank was designed with boiler use in mind.
I would throw the whole thing away like I have done to thousands of them over the years.
I changed one bladder. One time. I will never do it again. I don't want to even remember the experience let alone discuss it.